Even the king of the jungle is a thumb sucker

Western Sydney lion sucks keeper’s thumb

Thumb suckers of the world can rejoice in knowing that even the king of the jungle is among their ranks.

Kibulu the lion, who lives at Western Sydney's Zambi Wildlife Retreat, doesn't have thumbs of his own so it's handy that plenty of volunteers are more than happy to shove their hand into the mouth of one of the world's most notorious predators.

In his latest video, Kibulu is seen indulging in a little bit of thumb and slurping quite loudly – but he can probably get away with being noisy on account of his ability to eat a human alive.

It's a very cute video, but it's also the perfect video to show someone who tells you that you need to grow out of your juvenile habit.

And could just do for thumbsuckers what Billy Maddison did for third-grade pant wetters.

Kimbulu is renowned for loving a good suck of a thumb, with his habit making for some "aww" inspiring Instagram posts.

With his most recent video raking up thousands of likes in just two days there would be plenty of hands up to go into his gob but unfortunately the Zambi retreat is not open to the public – just yet.

Zambi is in the process of applying for a permit with the NSW government to allow the retreat to display the animals and run seminars, and while their website is calling the process "tedious", they are "slowly getting through all the paperwork".

Fingers – and thumbs – crossed that the paperwork comes through quickly.